<?php
/**
 * PHPExcel
 *
 * Copyright (c) 2006 - 2013 PHPExcel
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * @category   PHPExcel
 * @package    PHPExcel_CachedObjectStorage
 * @copyright  Copyright (c) 2006 - 2013 PHPExcel (http://www.codeplex.com/PHPExcel)
 * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt    LGPL
 * @version    1.7.9, 2013-06-02
 */


/**
 * PHPExcel_CachedObjectStorage_APC
 *
 * @category   PHPExcel
 * @package    PHPExcel_CachedObjectStorage
 * @copyright  Copyright (c) 2006 - 2013 PHPExcel (http://www.codeplex.com/PHPExcel)
 */
class PHPExcel_CachedObjectStorage_APC extends PHPExcel_CachedObjectStorage_CacheBase implements PHPExcel_CachedObjectStorage_ICache {

	/**
	 * Prefix used to uniquely identify cache data for this worksheet
	 *
	 * @access    private
	 * @var string
	 */
	private $_cachePrefix = null;

	/**
	 * Cache timeout
	 *
	 * @access    private
	 * @var integer
	 */
	private $_cacheTime = 600;


	/**
	 * Store cell data in cache for the current cell object if it's "dirty",
	 *     and the 'nullify' the current cell object
	 *
	 * @access  private
	 * @return  void
	 * @throws  PHPExcel_Exception
	 */
	protected function _storeData() {
		if ($this->_currentCellIsDirty)
		{
			$this->_currentObject->detach();

			if (!apc_store($this->_cachePrefix . $this->_currentObjectID . '.cache', serialize($this->_currentObject), $this->_cacheTime))
			{
				$this->__destruct();
				throw new PHPExcel_Exception('Failed to store cell ' . $this->_currentObjectID . ' in APC');
			}
			$this->_currentCellIsDirty = false;
		}
		$this->_currentObjectID = $this->_currentObject = null;
	} //    function _storeData()


	/**
	 * Add or Update a cell in cache identified by coordinate address
	 *
	 * @access  public
	 *
	 * @param   string        $pCoord Coordinate address of the cell to update
	 * @param   PHPExcel_Cell $cell   Cell to update
	 *
	 * @return  void
	 * @throws  PHPExcel_Exception
	 */
	public function addCacheData($pCoord, PHPExcel_Cell $cell) {
		if (($pCoord !== $this->_currentObjectID) && ($this->_currentObjectID !== null))
		{
			$this->_storeData();
		}
		$this->_cellCache[$pCoord] = true;

		$this->_currentObjectID = $pCoord;
		$this->_currentObject = $cell;
		$this->_currentCellIsDirty = true;

		return $cell;
	} //    function addCacheData()


	/**
	 * Is a value set in the current PHPExcel_CachedObjectStorage_ICache for an indexed cell?
	 *
	 * @access  public
	 *
	 * @param   string $pCoord Coordinate address of the cell to check
	 *
	 * @return  void
	 * @return  boolean
	 */
	public function isDataSet($pCoord) {
		//    Check if the requested entry is the current object, or exists in the cache
		if (parent::isDataSet($pCoord))
		{
			if ($this->_currentObjectID == $pCoord)
			{
				return true;
			}
			//    Check if the requested entry still exists in apc
			$success = apc_fetch($this->_cachePrefix . $pCoord . '.cache');
			if ($success === false)
			{
				//    Entry no longer exists in APC, so clear it from the cache array
				parent::deleteCacheData($pCoord);
				throw new PHPExcel_Exception('Cell entry ' . $pCoord . ' no longer exists in APC cache');
			}

			return true;
		}

		return false;
	} //    function isDataSet()


	/**
	 * Get cell at a specific coordinate
	 *
	 * @access  public
	 *
	 * @param   string $pCoord Coordinate of the cell
	 *
	 * @throws  PHPExcel_Exception
	 * @return  PHPExcel_Cell  Cell that was found, or null if not found
	 */
	public function getCacheData($pCoord) {
		if ($pCoord === $this->_currentObjectID)
		{
			return $this->_currentObject;
		}
		$this->_storeData();

		//    Check if the entry that has been requested actually exists
		if (parent::isDataSet($pCoord))
		{
			$obj = apc_fetch($this->_cachePrefix . $pCoord . '.cache');
			if ($obj === false)
			{
				//    Entry no longer exists in APC, so clear it from the cache array
				parent::deleteCacheData($pCoord);
				throw new PHPExcel_Exception('Cell entry ' . $pCoord . ' no longer exists in APC cache');
			}
		}
		else
		{
			//    Return null if requested entry doesn't exist in cache
			return null;
		}

		//    Set current entry to the requested entry
		$this->_currentObjectID = $pCoord;
		$this->_currentObject = unserialize($obj);
		//    Re-attach this as the cell's parent
		$this->_currentObject->attach($this);

		//    Return requested entry
		return $this->_currentObject;
	} //    function getCacheData()


	/**
	 * Get a list of all cell addresses currently held in cache
	 *
	 * @return  array of string
	 */
	public function getCellList() {
		if ($this->_currentObjectID !== null)
		{
			$this->_storeData();
		}

		return parent::getCellList();
	}


	/**
	 * Delete a cell in cache identified by coordinate address
	 *
	 * @access  public
	 *
	 * @param   string $pCoord Coordinate address of the cell to delete
	 *
	 * @throws  PHPExcel_Exception
	 */
	public function deleteCacheData($pCoord) {
		//    Delete the entry from APC
		apc_delete($this->_cachePrefix . $pCoord . '.cache');

		//    Delete the entry from our cell address array
		parent::deleteCacheData($pCoord);
	} //    function deleteCacheData()


	/**
	 * Clone the cell collection
	 *
	 * @access  public
	 *
	 * @param   PHPExcel_Worksheet $parent The new worksheet
	 *
	 * @throws  PHPExcel_Exception
	 * @return  void
	 */
	public function copyCellCollection(PHPExcel_Worksheet $parent) {
		parent::copyCellCollection($parent);
		//    Get a new id for the new file name
		$baseUnique = $this->_getUniqueID();
		$newCachePrefix = substr(md5($baseUnique), 0, 8) . '.';
		$cacheList = $this->getCellList();
		foreach ($cacheList as $cellID)
		{
			if ($cellID != $this->_currentObjectID)
			{
				$obj = apc_fetch($this->_cachePrefix . $cellID . '.cache');
				if ($obj === false)
				{
					//    Entry no longer exists in APC, so clear it from the cache array
					parent::deleteCacheData($cellID);
					throw new PHPExcel_Exception('Cell entry ' . $cellID . ' no longer exists in APC');
				}
				if (!apc_store($newCachePrefix . $cellID . '.cache', $obj, $this->_cacheTime))
				{
					$this->__destruct();
					throw new PHPExcel_Exception('Failed to store cell ' . $cellID . ' in APC');
				}
			}
		}
		$this->_cachePrefix = $newCachePrefix;
	} //    function copyCellCollection()


	/**
	 * Clear the cell collection and disconnect from our parent
	 *
	 * @return  void
	 */
	public function unsetWorksheetCells() {
		if ($this->_currentObject !== null)
		{
			$this->_currentObject->detach();
			$this->_currentObject = $this->_currentObjectID = null;
		}

		//    Flush the APC cache
		$this->__destruct();

		$this->_cellCache = array();

		//    detach ourself from the worksheet, so that it can then delete this object successfully
		$this->_parent = null;
	} //    function unsetWorksheetCells()


	/**
	 * Initialise this new cell collection
	 *
	 * @param  PHPExcel_Worksheet $parent The worksheet for this cell collection
	 * @param                     array   of mixed      $arguments  Additional initialisation arguments
	 */
	public function __construct(PHPExcel_Worksheet $parent, $arguments) {
		$cacheTime = (isset($arguments['cacheTime'])) ? $arguments['cacheTime'] : 600;

		if ($this->_cachePrefix === null)
		{
			$baseUnique = $this->_getUniqueID();
			$this->_cachePrefix = substr(md5($baseUnique), 0, 8) . '.';
			$this->_cacheTime = $cacheTime;

			parent::__construct($parent);
		}
	} //    function __construct()


	/**
	 * Destroy this cell collection
	 */
	public function __destruct() {
		$cacheList = $this->getCellList();
		foreach ($cacheList as $cellID)
		{
			apc_delete($this->_cachePrefix . $cellID . '.cache');
		}
	} //    function __destruct()


	/**
	 * Identify whether the caching method is currently available
	 * Some methods are dependent on the availability of certain extensions being enabled in the PHP build
	 *
	 * @return  boolean
	 */
	public static function cacheMethodIsAvailable() {
		if (!function_exists('apc_store'))
		{
			return false;
		}
		if (apc_sma_info() === false)
		{
			return false;
		}

		return true;
	}

}
